Hi all! I am working on a small project to trans-mux YouTube videos into a single file for playback in a social VR game.
I’m running into issues when using urisourcebin to download and de-mux the HLS playlist from YouTube.
This is my pipeline:
gst-launch-1.0 --gst-debug 3 `
matroskamux name=mux ! filesink location="video.mkv" `
urisourcebin uri="$(yt-dlp --get-url https://www.youtube.com/watch?v=q2RQyrp6j_A -f "bestaudio[ext=m4a]")" ! qtdemux ! audio/mpeg ! queue2 ! mux.audio_0 `
urisourcebin uri="$(yt-dlp --get-url https://www.youtube.com/watch?v=q2RQyrp6j_A -f "bestvideo[ext=mp4]")" ! video/x-vp9 ! vp9parse ! queue2 ! mux.video_0
These are the errors I’m seeing along with a corrupted video:
Setting pipeline to PLAYING ...
Buffering, setting pipeline to PAUSED ...
0:00:01.055796800 87356 00000178EA891F40 FIXME qtdemux qtdemux_types.c:269:qtdemux_type_get: unknown QuickTime node type vp09
Done buffering, setting pipeline to PLAYING ...
0:00:01.057932600 87356 00000178EA4D8280 FIXME basesink gstbasesink.c:3401:gst_base_sink_default_event:<filesink0> stream-start event without group-id. Consider implementing group-id handling in the upstream elements
Buffering, setting pipeline to PAUSED ...
0:00:01.060693200 87356 00000178EA4D8240 WARN matroskamux matroska-mux.c:4058:gst_matroska_mux_write_data:<mux:video_0> Invalid buffer timestamp; dropping buffer
Redistribute latency...
New clock: GstSystemClock
Redistribute latency...
Done buffering, setting pipeline to PLAYING ...
0:00:02.144258200 87356 00000178EA4D8240 WARN matroskamux matroska-mux.c:4058:gst_matroska_mux_write_data:<mux:video_0> Invalid buffer timestamp; dropping buffer
Buffering, setting pipeline to PAUSED ...
0:00:02.146744400 87356 00000178EA4D8240 WARN matroskamux matroska-mux.c:4058:gst_matroska_mux_write_data:<mux:video_0> Invalid buffer timestamp; dropping buffer
Redistribute latency...
Done buffering, setting pipeline to PLAYING ...
0:00:03.565762900 87356 00000178EA4D8240 WARN matroskamux matroska-mux.c:4058:gst_matroska_mux_write_data:<mux:video_0> Invalid buffer timestamp; dropping buffer
Interestingly enough, this pipeline does work, using souphttpsrc directly with the do-timestamp=true option:
gst-launch-1.0 --gst-debug 3 `
matroskamux name=mux ! filesink location="video.mkv" `
urisourcebin uri="$(yt-dlp --get-url https://www.youtube.com/watch?v=q2RQyrp6j_A -f "bestaudio[ext=m4a]")" ! qtdemux ! audio/mpeg ! queue2 ! mux.audio_0 `
souphttpsrc do-timestamp=true location="$(yt-dlp --get-url https://www.youtube.com/watch?v=q2RQyrp6j_A -f "bestvideo[ext=mp4]")" ! application/x-hls ! hlsdemux ! video/quicktime ! qtdemux ! video/x-vp9 ! vp9parse ! mux.video_0
Does anyone have any idea what might be going on here + why my buffer timestamps are invalid when using the newer urisourcebin & hlsdemux2?
I wanted to avoid using hlsdemux as it’s frequently been called old / deprecated and is in plugins-bad, but I cannot use hlsdemux2 manually as it’s auto-created inside of urisourcebin and requires a “streams aware” context.
Is there any way to pull this off without using the C API? I also tried with the Java bindings out of curiosity and wasn’t able to make it work by setting a “source-setup” callback on the urisourcebin to set do-timestamps=true on the souphttpsrc that is auto created…
Not really sure what to do. I would like to keep this a simple project and avoid running the pipeline from C or any bindings as this probably will 2-3x the code-base in size, but even with the bindings I’m having no luck. Is there any other pipeline element that can create buffer timestamps that I can just stick after urisourcebin to fix my issue? 
Something interesting that’s happening as well is mp4mux just straight up doesn’t work, it immediately exits with no error, despite MP4 from what I can tell being able to support VP9 codec. Also, playbin3 uri=xx works just fine as well 